The detectives investigate a string of murders. Could the killer be a police officer? Meanwhile, Rob is forced to hand over vital evidence when his family is threatened.
When a locksmith is murdered, Billie learns he was a witness to her father's death 10 years earlier. Vivienne pleads with her ex-husband to do the right thing, but he is afraid they're both in danger.
A body found in a suitcase is identified as a man who has been missing for several weeks. His widow and his brother point the finger at each other. Meanwhile, David tries to convince Mulgrew to reveal what he knows.
